Non-aqueous electrolyte cells containing anodes of alkali metals such as lithium, calcium, sodium and the like and high-energy cathodes of FeS, FeS.sub.2, CuO, CuS, Bi.sub.2 S.sub.3 and the like are often limited by conductivity within the cathode. To overcome this limitation, it is well known to add a conducting material such as carbon or graphite to the cathode. The addition of these materials, however, is known to contribute to an initially high open current voltage in many non-aqueous cells with alkali metal anodes and high energy cathodes. While such cells proceed to their lower operating voltage after time, the initial high voltage is unacceptable for many cell or battery applications which require a unipotential discharge.
A solution to this problem is disclosed in U.S. Pat. No. 4,163,829, which teaches that non-aqueous cells containing alkali metal anodes and high energy cathodes, which also contain graphite or carbon within the cathode to improve the conductivity thereof, will exhibit improved open circuit voltage characteristics if metallic zinc is used in conjunction with the cathode. The mere presence of zinc in electrical and ionic contact with the cathode is said to be sufficient for purposes of the improvement disclosed by the patent. It is postulated that the zinc which may be a discrete layer, a coating, a screen, a porous strip or a powder, acts as a metallic reducing agent to overcome the deleterious effect on OCV of oxygen present on the surface of the graphite or carbon. U.S. Pat. No. 4,163,829 discloses that of the several alkali metals which may be used as the anode material, lithium is preferred.
That patent also discloses that FeS is a preferred high energy cathode material, that 3-methyl-2-oxazolidone, propylene or ethylene carbonate, 1,2 dimethoxyethane and 1,3 dioxolane are the preferred electrolyte solvents and LiCF.sub.3 SO.sub.3 or LiClO.sub.4 are the preferred ionizing solutes. However, following the teaching of U.S. Pat. No. 4,163,829 does not improve the rate capacity of the non-aqueous cells described therein.
Accordingly, it is a primary objective of this invention to provide a non-aqueous alkali anode cell having a high energy density cathode material intermixed with minor amounts of zinc and sulfur and an alkali metal anode which exhibits improved rate capacity.
Another primary objective of this invention is to provide a process for producing a non-aqueous, alkali anode cell having a powdered high density cathode material, in which the cathode, after being intermixed with minor amounts of zinc and sulfur is subjected to a differential heat treatment in a protective atmosphere, which exhibits improved rate capacity.
Another objective of the invention is to provide a lithium-organic electrolyte cell having an FeS cathode, intermixed with minor amounts of zinc and sulfur, which exhibits improved rate capacity.
Another objective of the invention is to provide a process for producing a lithium-organic electrolyte cell, having a cathode of FeS, produced from FeS powder which, after being intermixed with minor amounts of zinc and sulfur, is subjected to a differential heat treatment in a protective atmosphere, and exhibits improved rate capacity.